Method and apparatus for processing logs

ABSTRACT

A method and apparatus for processing logs to obtain an optimum amount of wood products of predetermined quality from each log. The method includes the steps of positioning each log along a reference axis, electronically scanning the log to determine certain of its dimensions with respect to the reference axis, computing the center axis of the largest surface of a preselected shape that can be superimposed within the measured dimensions, and repositioning the log with the center axis parallel to an index line such as the cutting line of a predetermined processing equipment. Scanning arrangements and processing apparatus are disclosed for practicing the steps of the method in the processing of logs of different diameters.

June 5, 11973 United States atet [191 Mason [54] METHOD AND APPARATUSFOR Primary ExaminerD0nald R. Schran PROCESSING LOGS Attorney-Daniel P.Chernoff and Jacob E. Vilhauer, Inventor:

Howard C. Mason, Oregon City, Oreg.

[57] ABSTRACT A method and apparatus for processing logs to obtain [73]Assignee: Sun Studs, Inc., Roseburg, Oreg.

Nov. 25, 1970 [22] Filed:

an optimum amount of wood products of predeter- [21] Appl. No.: 92,581mined quality from each log. The method includes the steps ofpositioning each log along a reference axis, electronically scanning thelog to determine certain of its dimensions with respect to the referenceaxis, computing the center axis of the largest surface of a preselectedshape that can be superimposed within the measured dimensions, andrepositioning the log with the center axis parallel to an index linesuch as the 0 2 M133 4 9 M W0; 2 B M :5 4 M W34 4 "4 1N4 Sh C n r a u en S L m C s t UIF NIH 555 [ll [56] References Cited UNITED STATESPATENTS cutting line of a predetermined processing equipment. Scanningarrangements and processing apparatus are disclosed for practicing thesteps of the method in the processing of logs of different diameters.

3,459,246 8/1969 Ottosson...........................144/312R 3,037,5386/1962 Graham............................144/209A 5 Claims, 7 DrawingFigures Patented June 5, 1973 3 Sheets-Sheet 2 i n 87 [I mall]: 66 75 627067"/ 55 F I24 7 HOWARD c. MASON INVENTOR BY /%Z v W ATTY Patented June5, 1973 3 Sheets-Sheet 5 llllllllllmlllllll M fez FIG. 7

lllllllllllllllllll] HOWARD C. MASON I NVENTOR ATTY.

METHOD AND APPARATUS FOR PROCESSING LOGS BACKGROUND OF THE INVENTION Thepresent invention relates to a method and apparatus for the processingof logs to produce optimum results. More particularly, the invention isrelated to a method and apparatus for the processing of logs ofdifferent diameters to obtain the maximum amount of salable woodproducts of a predetermined quality from each log.

In processing logs, such as in peeling veneer or sawing logs into cutlumber, it is desirable to obtain the maximum amount of salable woodproducts of high quality from each log. New saws and saw arrays, as wellas improved methods of treating and softening logs, are continuouslybeing developed to permit the processing of logs with a minimum of woodwastage. However, a major problem still exists in the wood industry indetermining how a given log should be divided in an optimum fashion, andthen in automatically controlling a predetermined processing equipmentto divide the log in the selected fashion.

It is conventional in the lumber industry to reduce logs to cut lumberby means of a saw array, and a saw carriage that is movable with respectto the saw array under the control of an operator. Prior to gripping ofa given log in the saw carriage, the log is positioned with its bestside up, as determined from a visual inspection by the operator. Withthe log aligned with its best side up, (i.e., usually the side most freefrom crooks), the log is gripped in the saw carriage and moved throughthe saw array repeatedly, with cants or flitches of various widths beingremoved from the log on each pass as determined arbitrarily by theoperator in accordance with certain rules of thumb.

In such practice, many factors are not considered that should enter intoa determination of the optimum manner of dividing or breaking down agiven log. For example, all logs are tapered from one end to the other.Consequently, some wastage always occurs in producing lumber of regularor rectangular dimensions therefrom. Furthermore, logs are commonly ofvery irregular and/or elliptical diameter, and include crooks alongtheir length, as well as depressions or extensions in their outersurfaces. For obvious reasons, each of these factors has a significanteffect upon the way the log should be divided to achieve optimumresults. Accordingly, it would be desirable to eliminate operatorjudgment from the determination of how to divide each given log, infavor of a system which would precisely and automatically evaluate allthe above factors in arriving at an optimum solution.

US. Pat. No. 3,459,246 to Ottosson represents an advance in the art inthis regard in that it describes an apparatus for sawing logs thatincludes an automatically controlled saw array. The Ottosson systemfurther includes means for examining an incoming log with a photocellarray to determine the smallest diameter of the log, and uses thisinformation to automatically set the saw array for dividing the log. Inother words, in the Ottosson system, each log is sawed in accordancewith a programmed cutting schedule determined by the measured minimumdiameter of the log. This tends to reduce the wastage that occurs as aresult of log taper, and can partially compensate for irregularities inthe logs surface that result in a noticeable reduction in the logdiameter.

However, the Ottosson system does not include means for repositioning alog after scanning. Consequently, a crooked log of a given diameter isprocessed in the same fashion as a straight log of the same diameter,with significant wastage resulting. Furthermore, unnecessary wastageresults due to the other factors such as elliptical diameter andirregular surface depressions and extensions. Therefore, the Ottossonsystem does not produce optimum results in the division of logs into cutlumber.

SUMMARY OF THE INVENTION Accordingly, it is an object of the inventionto provide a method and apparatus for processing logs that overcomes thedisadvantages of conventional methods.

It is another object of the invention to provide a method for processinglogs to obtain the maximum amount of wood products of a predeterminedquality from a given log.

It is a further object of the invention to provide a method forprocessing logs wherein certain dimensions of each log are accuratelymeasured and the largest surface of a preselected shape that can besuperimposed within the measured dimensions is determined.

It is yet a further object of the invention to provide apparatus forrepositioning the log with respect to a predetermined processingequipment for maximum utilization of the wood encompassed by suchsurface.

It is yet a further object of the invention to provide novel apparatusfor practicing the method described herein.

The inventor of the method and apparatus described herein has determinedthat there is an arithmetical best solution for the division of eachcircular area of a different diameter, such as a log cross section, intorectangular components of a given size or set of sizes, such as thecross sections of pieces of cut lumber. The inventor also has found thatto obtain the maximum amount of salable wood products from a given log,it is desirable to measure accurately certain of the dimensions of thelog and to determine the largest surface of preselected shape that canbe superimposed within the measured dimensions of the log.

If the log is to be reduced to cut lumber or veneer the preselectedsurface should have parallel sides. Therefore, if the log is measured intwo dimensions so that a planar profile of the log can be plotted, aplanar surface such as a rectangle or parallelogram is selected.However, if the log is measured in three dimensions so that a volumetricrepresentation of the log can be plotted, a volumetric surface such as acylinder is selected. In either case, the largest surface of thepreselected form that can be superimposed within the measured dimensionsof the log encompasses the maximum amount of lumber within the log thatcan be reduced to cut lumber of the desired rectangular dimensions orreduced to veneer. In the event the log is to be divided into irregularcomponents, an appropriate surface of irregular form could be selected,although this is not a usual requirement of log processing systems.

Accordingly, the above objects of the invention are attained by a methodwhich includes the steps of positioning a log along a reference axis,scanning the log to determine certain of its dimensions, computing thecenter axis of the largest surface of preselected form (such as arectangle or a cylinder) that can be superimposed within the measureddimensions of the log, and repositioning the log with the center axisparallel to an index line such as the cutting line of a predeterminedprocessing equipment, allowing maximum use of the wood encompassedwithin such surface. The method can be utilized in producing cut lumberfrom logs, or it can be utilized in other log processing operations suchas peeling veneer.

Scanning arrangements and an automatically controlled sawmill aredescribed for processing logs of different diameters.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of theinvention will become apparent from the following detailed descriptionof the invention taken in conjunction with the accompanying drawings,wherein:

FIG. 1 is a schematic diagram of a sawmill adapted to process lumber inaccordance with the invention;

FIG. 2 is a diagrammatic side elevation view of a scanner and blockcharger for positioning logs, of the type used in the apparatusillustrated in FIG. 1;

FIG. 3 is a partial top elevation view of the scanner and block chargershown in FIG. 2, illustrating the outline of a log as initiallypositioned in the charger;

FIG. 4 is a diagrammatic view of a scan grid illustrating the axialalignment of a log before scanning and the axial alignment of the samelog as repositioned in the charger of FIG. 2 just prior to engagement inthe saw carriage;

FIG. 5 is a diagrammatic side elevation view of a cant scanner andcharger assembly of the type used for positioning cants in the sawmilldisclosed in FIG. 1;

FIG. 6 is a top elevation view of the cant scanner assembly illustratedin FIG. 5 with a cant positioned for scanning therein; and

FIG. 7 is a diagrammatic view of a scan grid illustrating the axialalignment of a cant before scanning and the axial alignment of the samecant as repositioned for further processing upon leaving the cantscanner illustrated in the FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION According to the invention, logsof different diameter are automatically processed to obtain an optimumamount of salable wood products of a predetermined quality from eachlog. Each log is supplied to a processing apparatus and aligned in acharger along a reference axis. The log is then examined, such as by aphotoelectric scanning device, to accurately determine certain of thedimensions of the log.

The scanning can be carried out in numerous ways. One convenient way ofscanning the log is to utilize a single array of photoelectric scanningdevices generally positioned along the length of the log and oriented toscan the log along one side for measuring the length of the log and thediameter of the log at spaced intervals along the length thereof. Thispermits the plotting of a two-dimensional representation or planarprofile of the log. The term plotting" is used to mean the orientationof data representations within data processing equipment and notphysical plotting, although the latter is possible. After the firstscanning operation, the log is repositioned in the log processingapparatus and divided into subcomponents such as cants or flitches.

The cants or flitches are then rescanned along a flat side prior tobeing processed into cut lumber.

Alternatively, a single set of scanning devices can be used, and the logcan be periodically rotated beneath the scanning devices, to derive aseries of readings that measure the spaced diameters of the log at thedifferent angular positions. This permits the plotting of a threedimensional representation of the log.

In yet another scanning method, two arrays of scanning devices arepositioned along the length of the log, oriented in different planes(for example, at right angles to each other) to simultaneously measurethe spaced diameters of two different sides of the log. This method ofscanning also permits the plotting of a three dimensional representationof the log.

The dimensional data derived from the scanning devices is supplied to anelectronic data processing unit for evaluation or plotting. From thedimensional data, the electronic data processing unit produces an outputthat represents the coordinates of the largest surface of preselectedform that can be superimposed within the measured dimensions of the logtaking into account certain arbitrary factors that relate to thepredetermined acceptable quality of the wood products to be derived fromthe log. As previously explained, if the scanning device used in onefrom which a planar profile of the log can be plotted a planar surfacewith parallel sides, such as a rectangle or parallelogram, is selected.However, if a scanning device is used which produces data from which avolumetric profile of the log can be plotted, a volumetric surface withparallel sides, such as a cylinder, is selected. In addition, the outputof the data processing unit includes information representing thecoordinates of the center axis of the selected surface. The outputsignals of the data processing unit are used to control therepositioning of the log in a carriage with the calculated center axisparallel to an index line such as the cutting line of a saw array.

Upon evaluation of the dimensional information the data processing unitalso selects, from a number of possible sawing or processing patternsthat were previously designed by empirical methods and stored in theprocessing unit memory, a processing pattern which is the optimumpattern for the largest surface. Such an optimum pattern is the patternthat will yield the maximum amount of wood products of a desired qualityfrom the given log. For example, if it is desired to divide a log into 2inch X 4 inch studs, the optimum pattern would produce the greatestpossible number of studs of acceptable quality from the given log. Afterselection, the processing program for the selected pattern isautomatically carried out by the processing apparatus under the controlof the data processing unit.

The method described herein can be used with saw arrays for producingcut lumber from logs, or can be used with other processing apparatussuch as that used for peeling veneer.

One preferred apparatus for practicing the method of the invention isillustrated in the drawings in the form of a sawmill especially adaptedfor sawing logs into cut lumber such as 2 inch X 4 inch studs. Thesawmill is designed for processing, continuously, logs of predeterminedlengths ranging from 84 to 104 inches and having different diameters,for example ranging from 5 to 50 inches.

In accordance with the method of the invention, each of the logs,referred to hereinafter as blocks, is scanned along one side whereby aplanar profile of the dimensions of the log can be plotted, and isregarded as including a volume of usable wood encompassed within thelargest parallelogram that can be superimposed within the measureddimensions. The center axis of the optimum surface or parallelogram fora given block is also determined from data obtained during photoelectricscanning of one side of the log. The best or optimum solution fordividing each block is the solution that provides the greatest number ofcants of 2 inch or 4 inch width and is determined after making allowancefor such lumber grading factors such as acceptable sawing variations,shrinkage, surfacing, saw kerf, and for allowable wane consistent withacceptable grade standards. After a block is divided into cants, thecants are scanned along a flat side whereby a planar profile of eachcant is plotted. An optimum solution is then determined for dividingeach cant into the maximum number of studs of 2 inch X 4 cross section.

Referring now to FIG. 1, a sawmill is generally illustrated including ablock infeed network 11, a charger and scanner array 12, a saw carriage14, and a twin band mill 15. The sawmill further includes anintermediate transfer conveyer arrangement 16 interconnecting the bandmill with a cant scanner generally indicated at 18. A cant guide 19 isarranged between scanner l8 and a cant processing station 20 thatincludes a 4 inch gang edger 21 and a 2 inch gang edger 22. A conveyorsystem generally indicated at 25 receives cut lumber from the edgers andprecedes an unscrambler 26 and a sorter 27 that ultimately supply sortedlumber to a stacker 29. A data processing unit generally indicated at 30is provided for automatically controlling all the components of thesawmill in a manner explained hereinafter. It should be understood thatthe conveyors and chains shown in the drawings are of conventionaldesign and are schematically illustrated to permit simplication of thedrawings. Suitable power means, not shown, are associated with each ofthe conveyors and chains to drive them at the desired speeds in thedirections indicated by the arrows.

Referring more particularly to the components mentioned above, blockinfeed network 11 includes a horizontal block infeed chain 35, and aninclined block infeed chain 36 arranged at the rear of chain 35. infeedchain is adapted to receive blocks deposited thereon, for example bymeans of a lift truck, and both chains are adapted for transferringblocks therealong.

dicated, at a lower level than block infeed chain 35.

Therefore, operator controlled ejection means, not shown, can be usedfor transferring reject blocks from the infeed chain to chain 41 fortransport to the chipper.

A conveyor 46 and a transfer chain 47 are arranged to communicatebetween chain 41 and a cutoff saw 49, having an infeed roller set 50associated therewith. The cutoff saw is a conventional unit adapted forreducing logs to a suitable block size for processing in the chipper.The sawmill also includes an inclined conveyor chain 51 adapted tocommunicate directly with chipper 34.

Referring now to FIGS. 1-3, the block charger and scanner array 12 areparticularly illustrated as comprising a block alignment yoke 55including two sets of vertically opposed V-members or Vs 56. Each set ofVs includes a fixed lower V 58 and an upper V 59 adapted for powermovement between a closed or clamped position shown in solid outline inFIG. 2 and an open or retracted position shown in dotted outline in FIG.2.

The lower Vs are positioned beneath the upper end of chain 36 and aresuitably constructed to receive and support blocks as they leave the endof chain 36. The upper Vs occupy a noninterfering position whenretracted and are adapted for gripping and firmly clamping blocksagainst the lower Vs when closed. The block is centered in the Vs andretained in a fixed position along a lengthwise axis that is arbitrarilyused as a reference axis during the scanning operation describedhereinafter. It should be apparent that the reference axis is notcoincident with the center axis of the log, but the reference axis willalways pass through the ends of the log.

The positioning of the upper Vs is automatically controlled byprocessing unit 30. However, a manually controlled override switch and ablock rotating mechanism, not shown, are provided by which the V's canbe opened and the block rotated for realignment. This enables each blockto be clamped in the block alignment yoke with its best side up asdetermined by an operator.

A block charger 60 is provided in conjunction with the alignment yoke,having arms 62, 64 positioned outwardly on either side of the V-membersto selectively engage the ends of a block clamped within yoke 55. Forthis purpose, each charger arm includes an enlarged outer portion 66having spikes 67 fastened thereto. Each charger arm otherwise includes amultiposition stacked hydraulic cylinder set works 70 adapted forextending the length of the arm, independently, in increments, such as 1[10th inch increments. The upper end 69 of each charger arm is securedto a power assembly 72 controlled by processing unit 30. The powerassembly is adapted for moving the arms, selectively, into and out ofcontact with the ends of a block in yoke 55. in addition, the powerassembly is designed to pivot the charger arms upwardly, to the positionb shown in dotted outline in FIG. 2, wherein a block carried thereby isgenerally positioned along a scanning path indicated at 74. The powerassembly is further adapted for driving the charger arms and block as aunit whereby the block traverses path 74 through a block scanner 75 andultimately is rested in a region adjacent saw carriage 14 in position 0shown in dotted outline in FIG. 2. During this entire phase of theoperation the block is positioned along the reference axis, runninglongitudinally of the block, as determined by the original positioningof the block in the alignment yoke 55.

Referring to FIGS. l-3, the block scanner 75 is particularly illustratedas comprising an upper hood 77 and a lower hood 79 spaced therefrom. Theupper hood is positioned above scan line 74 and serves as a housing andreflector for a line source of light 80, such as a neon tube, supportedtherefrom and extending parallel to the length of a block oriented inthe charger arms. Source 80 produces light of appropriate intensity anddirection to illuminate the upper half of each block as it traverses thescanner. Lower housing 79 supports a plurality of light responsiveelements 82, such as photocells and electrical circuitry associatedtherewith. The photocells are arranged in a line directly beneath lightsource 80 for exposure thereby, being interspersed at predeterminedintervals along the length of lower hood 79. The photocells are adaptedto produce an electrical output in the presence of light and to produceno output in the absence of light. Accordingly, the presence of anyportion of a block between light source 80 and each individual photocellcan be detected.

In the preferred embodiment illustrated 55 photocells are utilized beingspaced at 2 inch intervals over a 110 inch span along the length of thescanner. The output of each photocell is connected to a conventionalelectronic unit, not shown, for amplifying the output of the photocelland supplying the amplified output to processing unit 30. In theembodiment illustrated, the photocell array is actuated, by means notshown, upon the approach of the charger arms and 550 readings areobtained from each photocell during the traverse of a given block, eachreading being taken at a 1 10th inch interval of horizontal travel ofthe block through the scanner. The data procured from such a scanningsequence is supplied to processing unit 30 and utilized in thecalculation and plotting of the block dimensions. From such dataprocessing unit 30 calculates the center axis of the largestparallelogram that can be superimposed within the measured and plotteddimensions of the block and independently controls the operation of thehydraulic set works 70 of each charger arm 62, 64 to realign the blockwith the center axis parallel to an index line, such as a saw line,prior to engagement in the saw carriage, in a manner explained in moredetail hereinafter.

Saw carriage 14 is of conventional design, including spaced-apartcarriage arms 83, 84 adapted to engage the ends of a block. Conventionalmeans, not shown, are provided for moving the carriage arms intoengagement with a block and for releasing the arms at the end of thesawing program. The carriage arms are formed with knife edges 86designed to slice into the ends of recesses 87 formed therein, locatedso as to be centered over ends 66 of the charger arms when a block isengaged by carriage arms 83, 84. This permits gripping of the block inthe saw carriage along the calculated center axis prior to release ofthe block by the charger arms.

Conventional means, not shown, are provided for driving the carriagearms, with a block gripped therein, along an index line such as acarriage center line or saw line 90 between a start position 91indicated in FIG. 1 and a stop position 92. Intermediate stops at abackstand position 94 are also possible. A conventional slab chipper 95is provided having heads 96 arranged on either side of the carriagecenter line between the start and backstand positions for removal ofchips from the outer periphery of the blocks. The spacing of the slabchipper heads is automatically controlled by unit 30.

Twin band mill 15 is arranged along center line 90 for removing slabsfrom either side of a block traversing the center line. The band mill isof conventional design, comprising a pair of band saws 98, 99. Each bandsaw includes front and rear cutting edges and is adapted for selectivelateral movement toward or away from center 7 line 90 in response tosignals from processing unit 30.

Conveyors 101, 102 and rollers 103, 104 are adapted to receive cantsremoved from the blocks on forward passes;'and conveyors 107, 108 arearranged to receive cants removed from the blocks on rearward passes.

A main outfeed conveyor 110 is provided for receiving cants from theband mill. The main conveyor communicates with conveyor 107 by means ofa conveyor 112, and with conveyor 108 by means of a series of conveyors113, 114, 115. A conveyor 116 is adapted to receive cants from conveyors101,, 102 and deliver them to the main outfeed conveyor. Intermediatetransfer conveyor 118 is adapted to receive cants from outfeed conveyor110 via chain 119 and to deliver such cants to cant scanner 18.

Referring now to FIGS. 5 and 6, the cant scanner is particularlyillustrated as including a pair of parallel scan chains 121 each havinga plurality of lugs 122 secured thereto in opposed pairs or sets, and apair of crowder chains 124 arranged parallel with and overlying the scanchains. Cants are received on the scan chains from transfer conveyor 118and are conveyed thereby through the cant scanner. The cants, such ascant 130, are arranged on the scan chains with their length transverseto the direction of movement of the chain. The cants are also positionedby conventional means with their worst side up, (i .e., the side havingthe narrowest strip of smooth surface) as illustrated in FIGS. 5 and 6.

Lugs 122 on the scan chains extend above the level of the crowder chainsand the crowder chains are operated at a higher speed than the scanchains. Therefore, each cant is maintained in contact with a set of lugson the cant chain during transfer through the cant scanner. Thedifference in speeds between the crowder chain and the cant chain isadjusted to a suitable value to maintain the cants in firm contact withthe lugs.

The cant scanner comprises a hood 131 supported above the cant chainsthat serves as a reflector element and as a support for a plurality ofdetectors such as photocells 133. A pair of light sources such as lamps135, 136 are supported on either side of the hood arranged to directlight upon the upper surface of each cant as it is guided beneath thehood. The light from these lamps is reflected by the smooth surfaces ofthe cant upwardly to the photocells. However, any light striking therough or wane surfaces of the cant is absorbed or diffused whereby thephotocells do not receive it. Accordingly, the photocells accuratelydetect the dimensions of the flat surface on the upper side of the cant.In the preferred embodiment 55 photocells are utilized, arranged in linealong a 110 inch axis passing through the center of the scanner hood. Aswith the block scanner, a scan grid 55 inches wide is utilized, withmeasurements of the cant being taken every onetenth inch of itstransverse of the scan grid. Therefore, the output data from thephotocell array can be supplied to unit 30 where it is processed forcalculation of an optimum parallelogram of wood of uniform thickness inthe cant, as well as the center axis thereof.

A conveyor 140 is provided for receiving cants from the crowder chain,after scanning, and delivering such cants to a conveyor 142 having a setof cant guides 19 associated therewith. Each cant guide includes a stop147 that is independently positioned by a hydraulic ram 148 at a desiredlateral distance from the edge of conveyor 142. The stops of both cantguides are adjusted, under the control of processing unit 30, to contactthe leading edge of the cant and to establish a desired alignment foreach cant as it is projected onto conveyor 142. Thus, the cants arerealigned or repositioned with the center axis of the optimumparallelogram parallel to the cutting line of the edger saws.

A cant chipper 144 is arranged downstream of conveyor 142 for removingany excess portions of the cants prior to sawing, and a conveyor 146 isadapted to receive cants leaving the cant chipper. Four inch gang edger21 is arranged downstream of conveyor 146. A transfer conveyor 150 andan edger infeed conveyor 152 are arranged upstream of 2 inch gang edger22. A selector fence 156 of conventional design is associated withconveyor 146. The fence permits passage of 2 inch cants and controls thetransfer of 4 inch cants to the transfer chain for delivery to the 2inch gang edger. Consequently, in the embodiment illustrated, all thecut lumber is reduced to 2 inch X 4 inch studs. It should be apparent,however, that other sawing arrangements are possible without departingfrom the invention.

An outfeed conveyor 160 receives cut lumber from gang edger 21 and acorresponding outfeed conveyor 162 receives cut lumber from gang edger22. The cut lumber is delivered to an unscrambler 26 via a transferconveyor 166, a conveyor 167, and a cross conveyor 169. The unscrambleris of conventional design and provides aligned cut lumber to a sorter 27via a transfer conveyor 171.

A conventional stacking unit 29 is located downstream of the sorter. Thestacking unit serves to automatically stack the cut lumber or studs inpredetermined lots for delivery from the sawmill.

The operation of the sawmill described hereinbefore is automaticallycontrolled by means of data processing unit 30, with the exception ofcertain operator responsive override controls, such as the blockrotating control previously mentioned. Blocks are transmitted into themill for processing via the block infeed conveyors and reach thealignment yoke. When a block drops into the lower Vs of the yoke, the Vsautomatically close and clamp the block in a position along a referenceaxis such as that illustrated in FIG. 3.

Ordinarily, it is preferred that the block be positioned with the bestside up. Therefore, after the clamping action, if the operator observesthat the block is not so positioned, he can reopen the Vs, rotate theblock on the lower Vs until its principal curvature or any excessivesurface irregularity is arranged in a vertical plane. The Vs are thenpermitted to reclamp the block in that position and the block chargerarms automatically grip the block at each end, in response to processingunit control signals. The Vs then retract allowing the charger arms topivot the block upwardly and move it horizontally along the scan path.

As the block approaches the scan zone, the photocell array is actuatedand scanning begins at a point corresponding to the zero line of theblock scan grid schematically represented in FIG. 4. During the passageof the block through the scan zone, a signal is generated from eachphotocell for each one-tenth inch of block travel through the 55 inchscan zone. As light is occluded by portions of the block, the recordedsignal from each of the blocked photocells changes whereby the profileof the leading edge of the block is detected. When the trailing edge ofthe block passes by a particular photocell, the signal from thatphotocell again changes whereby the profile of the trailing edge of theblock is detected.

When the last point on the trailing side of the block has passed thephotocell array, the data supplied to the processing unit is used in thecomputation of the maximum parallelogram which can be superimposedwithin the profile dimensions of the block. The center axis of themaximum parallelogram is also calculated and an electrical signalrepresenting that center axis is transmitted to the charger arm setworks. As the charger arms approach a position adjacent the sawcarriage, the electrical signal from the processing unit controls themovement of the calibrated stacked hydraulic cylinders comprising theset works. The hydraulic cylinders are extended, individually, until thecenter axis of the optimum parallelogram is parallel with the sawingline of the saw carriage. The center axis can coincide with the sawingline or it can be offset therefrom by a small distance as is required bythe particular cutting program selected.

With the block properly repositioned, the saw carriage arms close oneach end of the block and the charger arms are released from the block.The charger arms are then withdrawn to their original location forhandling the next block fed into the sawmill.

Referring now to FIG. 4, a planar profile of a typical block is shown insolid outline superimposed upon a grid that schematically represents theblock scan grid. The parallelogram having the greatest width that can besuperimposed within the block profile is represented by parallelogram Xand the center axis of parallelogram X is represented by line Y. Line Rrepresents the position of the reference axis of the block duringscanning and line R represents the position of the reference axis afterthe block is repositioned in the saw carriage arms. It should beapparent that the block is repositioned after scanning so that centeraxis Y of parallelogram X is parallel to the base of the scan grid whichis, in turn, parallel to the saw line. As shown, such repositioningresults in the movement of both ends of the block which causes bothangular and lateral adjustment of the reference axis.

Before sawing, the processing unit 30 positions the slab chipper headsto convert a calculated amount of slab from each side of the block intochips, in accordance with the appropriate preselected cutting pattern.As previously mentioned, the sawing pattern for each particular block isautomatically selected by the processing unit from one of a number ofempirically determined cutting patterns that are retained in theprocessing unit, a different pattern being provided for each l/lOth inchdifference in width of the maximum parallelogram.

As the block is passing through the slab chipper, the two band saws ofthe twin band mill are moved into position for the first cuts, alsounder the control of the processing unit. When the band saws arepositioned, the saw carriage completes its first pass through the bandmill with the first pair of cants being removed, one from each side ofthe block, and delivered through the conveyor network previouslydescribed toward the cant scanner. The band saws are then repositionedfor the second cuts and the saw carriage and block are passed backthrough the band mill with the second set of cants being removed anddropped, one on each side of the block. This process is repeated untilthe selected cutting program for the block has been completed.

ill

Upon completion, the saw carriage stops in the backstand positionbetween the band mill and the slab chipper and releases the remainingsection of the block. The saw carriage then returns to the startposition to receive the next block to be processed.

It should be noted that it is possible for the processing to includeseveral passes of the block through the slab chipper in order to removeexcess wood such as would occur with a flared block. This serves toprevent damage to the chipper in the event it is necessary to removemore wood than the chipper is capable of on the first pass.

The cants are transferred sequentially from the outfeed conveyor andindexed onto the lugged scan chains. The cants are positioned on theintermediate transfer conveyor with their narrow side up as illustratedin FIG. 6 and are maintained in this relative position during theremaining sawing operations. Each cant is carried onto the scan chainsand maintained in contact with a set of lugs by the crowder chain. Theposition of the cant in contact with the lugs establishes a referenceposition for the cant during processing which is the equivalent ofgripping the cant along a reference axis M as shown in FIG. 6. Each setof lugs retains its cant aligned along the reference axis M duringtransfer through the cant scanner. Therefore, each individual cant canbe identified by its relative position during and after scanning. Thisfacilitates the housekeeping task of the processing unit since asignificant interval occurs between the scanning of a particular cantand the processing of that cant by the cant chipper and edger sawarrangement.

The cant scanning operation is similar to the block scanning operationpreviously described in that a 55 inch by 110 inch scan grid isutilized. In the embodiment described, 55 photocells are utilized,although a different number could be used if desired. The photocellarray is actuated as each set of lugs approaches the zero line of thescan grid and as the cant traverses the scan line an output signal isderived from each photocell during each one-tenth inch of cant movementacross the scan grid. As previously described, when light is reflectedfrom the smooth upper surface of the cant the photocell produces apositive output. However, when light strikes the wane portions of thecant or is diffused by a front or trailing edge of the cant, thephotocell produces no output. Accordingly, an accurate profile of theupper surface of the cant can be detected and measured.

As with the block scanner, data from each cant is processed in unit 30and the widest parallelogram of wood of uniform thickness encompassedwithin the profile of the cant is determined. Data representing thecenter axis of the parallelogram is also calculated and supplied to thecant guides. In response to this data, the two adjustable set stops atthe edge of the cant guide conveyor are set to predetermined positions.Accordingly, as the leading edge of the cant moves onto the conveyorinto contact with these set stops, the cant is automatically positionedwith the center axis of the optimum parallelogram of wood alignedparallel to the center line of the cant chipper and the edger saws. Thecant is maintained in this alignment during subsequent sawing.

Referring now to FIG. 7, the profile of a typical cant is shown in solidoutline superimposed upon a grid that schematically represents the cantscan grid. The widest parallelogram that can be superimposed within thecant profile is represented by parallelogram K and the center axis ofparallelogram K is represented by line L. Line M represents the positionof the reference axis of the cant during scanning and line M representsthe position of the reference axis after the block is retained onconveyor 142. It should be apparent that the cant is repositioned afterscanning so that the center axis L of parallelogram K is parallel to thebase of the scan line and parallel to the edger saws. As shown, suchrepositioning results in the movement of both ends of the cant, causingboth angular and lateral adjustment of the reference axis.

The processing unit also controls the movement of one or both heads ofthe cant chipper to locations which will convert to chips all except thewood within the widest parallelogram as the cant is driven through thechipper. As the edged cants leave the chipper they are carried byconveyor 146 into contact with fence 156. Two inch cants pass the fencemember and are ultimately processed through a 4 inch gang edger. The 4inch cants, however, are transferred by means of transfer conveyor 150and conveyor 152 for processing through the 2 inch gang edger.

From these saws, the resulting cut lumber is passed onto the conveyorsystems previously described and on through an unscrambler into thesorter. Studs from the sorter are usually made up into 7 foot kilnpackages in a stacker at the end of the sorter, at which point they canbe rolled out for transport to other areas, such as the drying kilns.

It should be apparent that in the sawmill described, the processingunits and conveying systems are arranged for convenient handling of cutlumber. However, other arrangements are possible without departing fromthe scope of the invention.

Likewise, the block scanner is particularly designed for convenientlyand accurately handling blocks of 8 foot lengths. However, otherscanning systems and scanning grids could be utilized so long as theblocks are repositioned along an optimum cutting axis. As previouslymentioned, it is possible to simultaneously scan the block along twoplanes to derive a threedimensional profile of the block. With suchscanning, it is possible to calculate in a single step the maximumcylindrical surface that can be superimposed within the dimensions of ablock. The block can then be repositioned with the center axis of thecylinder parallel to an index line for processing the block into cutlumber or into veneer.

In addition, with a single scanning array, a block could be repeatedlypassed through the scanner, being rotated a predetermined amount such as30, between each pass. This would produce data from the scanner outputwhich could also be utilized to derive a three dimensional profile ofthe block. The center axis of the largest cylindrical surface that couldbe superimposed within the block could be identified and the block couldthen be repositioned for processing as previously described. Thedisadvantage of such scanning is the additional time required. Inaddition, such scanning requires more intricate housekeeping" operationsin the processing unit. Therefore, such scanning is not preferred forthe processing of cut lumber.

However, it should be apparent that any of the types of scanningdescribed herein can be used to obtain more wood products from a givenlog than was heretofore possible. In addition, the invention describedresults in the automatic processing of blocks at a higher rate than waspreviously possible with a reduction in personnel.

It is claimed and desired to secure by Letters Patent:

1. A method of processing a log to obtain the optimum amount of woodproducts of a selected grade therefrom, comprising the steps ofpositioning the log with respect to a reference location,

scanning the log to determine certain of its dimensions with respect tothe reference location,

plotting in a data processing equipment at least one planar profile ofthe dimensions of the log, said profile being taken in a plane passingthrough the ends of the log,

computing in a data processing equipment at least the center axis of thewidest parallelogram that can be superimposed within the plotted profileof the log, and

repositioning the log with the center axis parallel to an index line' ofa log processing equipment.

2. Log processing equipment comprising a saw array aligned with an indexline,

aligning means for receiving and holding a log at a reference location,

photoelectric scanning means spaced from said reference location forproducing an output signal representative of the dimensions of a logpassed by said scanning means,

data processing means connected to said scanning means for evaluatingsaid output signal and producing a data output signal in responsethereto,

charger means for releasably gripping said log at said referencelocation and transporting the log past said scanning means, said chargermeans including means responsive to said data output signal forangularly repositioning said log with respect to said index line,

a saw carriage, aligned with said index line and movable with respect tosaid saw array, for receiving from said charger means said log whenrepositioned, and

control means associated with said saw carriage for selectively movingsaid carriage with respect to said saw array, said control means beingresponsive to said data output signal whereby said log carried by saidsaw carriage is divided into cants by the saw array in accordance with apreselected cutting pattern stored in said data processing means.

3. Log processing equipment as described in claim 2 further including amovable cant chain having means thereon for receiving and holding cantseach at a reference position,

transfer conveyor means for receiving cants produced by said saw arrayand conveying said cants onto said cant chain,

cant scanning means for producing a cant output signal representative ofthe profile dimensions of a cant passed by said scanning means whilebeing carried on said cant chain, said profile being taken along a flatside of said cant,

said data processing means being connected to said cant scanning meansfor evaluating said cant output signal and producing a cant data outputsignal in response thereto,

a cant sawing station spaced from said cant scanning means, including asawing conveyor and a saw array aligned along a second index line withrespect to said sawing conveyor, and

second transfer conveyor means for receiving cants from said cant chainand conveying said cants onto said sawing conveyor, said second transferconveyor means including adjustable cant guide means responsive to saidcant data output signal from said data processing means forrepositioning each cant with respect to said second index line beforesawing thereof by said saw array.

4. The method of claim 1 further including the steps dividing the loginto cants,

positioning each cant with respect to a cant reference position,

scanning each cant to measure certain of its dimensions with respect tothe reference position,

plotting in said data processing equipment a planar profile of themeasured dimensions of the cant, said profile being taken along a flatside of said cant,

computing in said data processing equipment the center axis of thewidest parallelogram that can be superimposed within the plotted profileof the cant, and

repositioning the cant with the center axis parallel to an index line ofa cant sawing array.

5. A method of processing a log including the steps placing the log in areference position,

scanning the log to measure the diameter of the log at numerouslocations spaced along the length of the log,

plotting in a data processing equipment a profile of the measureddiameters of the log,

computing in said data processing equipment the coordinates with respectto said reference position of the cylindrical surface having the largestdiameter defined within said plotted profile, and

repositioning said log with the sides of said cylindrical surfaceparallel to an index line of a log processing apparatus.

V UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTlON Patent No. 3 7 59 53 Dated JWE 5. 1973 Inventor(s) Howard C. Mason and Fred Sohn It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

The invention is a joint invention of Howard C. Mason and Fred Sohn,rather than a sole invention of Howard C. Mason alone.

Column 4, line 26, change "in"'to --is-.

Signed and sealed this 21st dayof May 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. c. MARSHALL DANN Attesting Officer I Commissionerof Patents FORM PO-IOSO (10-69) USCOMM-DC 60376-P69 U.5 GOVERNMENTPRINTING OFFICE: I969 0366-$34

1. A method of processing a log to obtain the optimum amount of wood products of a selected grade therefrom, comprising the steps of positioning the log with respect to a reference location, scanning the log to determine certain of its dimensions with respect to the reference location, plotting in a data processing equipment at least one planar profile of the dimensions of the log, said profile being taken in a plane passing through the ends of the log, computing in a data processing equipment at least the center axis of the widest parallelogram that can be superimposed within the plotted prOfile of the log, and repositioning the log with the center axis parallel to an index line of a log processing equipment.
 2. Log processing equipment comprising a saw array aligned with an index line, aligning means for receiving and holding a log at a reference location, photoelectric scanning means spaced from said reference location for producing an output signal representative of the dimensions of a log passed by said scanning means, data processing means connected to said scanning means for evaluating said output signal and producing a data output signal in response thereto, charger means for releasably gripping said log at said reference location and transporting the log past said scanning means, said charger means including means responsive to said data output signal for angularly repositioning said log with respect to said index line, a saw carriage, aligned with said index line and movable with respect to said saw array, for receiving from said charger means said log when repositioned, and control means associated with said saw carriage for selectively moving said carriage with respect to said saw array, said control means being responsive to said data output signal whereby said log carried by said saw carriage is divided into cants by the saw array in accordance with a preselected cutting pattern stored in said data processing means.
 3. Log processing equipment as described in claim 2 further including a movable cant chain having means thereon for receiving and holding cants each at a reference position, transfer conveyor means for receiving cants produced by said saw array and conveying said cants onto said cant chain, cant scanning means for producing a cant output signal representative of the profile dimensions of a cant passed by said scanning means while being carried on said cant chain, said profile being taken along a flat side of said cant, said data processing means being connected to said cant scanning means for evaluating said cant output signal and producing a cant data output signal in response thereto, a cant sawing station spaced from said cant scanning means, including a sawing conveyor and a saw array aligned along a second index line with respect to said sawing conveyor, and second transfer conveyor means for receiving cants from said cant chain and conveying said cants onto said sawing conveyor, said second transfer conveyor means including adjustable cant guide means responsive to said cant data output signal from said data processing means for repositioning each cant with respect to said second index line before sawing thereof by said saw array.
 4. The method of claim 1 further including the steps of dividing the log into cants, positioning each cant with respect to a cant reference position, scanning each cant to measure certain of its dimensions with respect to the reference position, plotting in said data processing equipment a planar profile of the measured dimensions of the cant, said profile being taken along a flat side of said cant, computing in said data processing equipment the center axis of the widest parallelogram that can be superimposed within the plotted profile of the cant, and repositioning the cant with the center axis parallel to an index line of a cant sawing array.
 5. A method of processing a log including the steps of placing the log in a reference position, scanning the log to measure the diameter of the log at numerous locations spaced along the length of the log, plotting in a data processing equipment a profile of the measured diameters of the log, computing in said data processing equipment the coordinates with respect to said reference position of the cylindrical surface having the largest diameter defined within said plotted profile, and repositioning said log with the sides of said cylindrical surface parallel to an index line of a log processing apparatus. 